U.S. patent number 10,042,006 [Application Number 14/301,944] was granted by the patent office on 2018-08-07 for battery state of health estimation using charging resistance equivalent.
This patent grant is currently assigned to GM Global Technology Operations LLC. The grantee listed for this patent is GM Global Technology Operations LLC. Invention is credited to Xinyu Du, Mark J. Rychlinski, Yilu Zhang.
United States Patent |
10,042,006 |
Du , et al. |
August 7, 2018 |
Battery state of health estimation using charging resistance
equivalent
Abstract
A number of illustrative variations may include a method of
estimating battery health including using a charging resistance
equivalent.
Inventors: |
Du; Xinyu (Oakland Township,
MI), Zhang; Yilu (Northville, MI), Rychlinski; Mark
J. (Farmington Hills, MI) |
Applicant: |
Name |
City |
State |
Country |
Type |
GM Global Technology Operations LLC |
Detroit |
MI |
US |
|
|
Assignee: |
GM Global Technology Operations
LLC (Detroit, MI)
|
Family
ID: |
54835970 |
Appl.
No.: |
14/301,944 |
Filed: |
June 11, 2014 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20150362561 A1 |
Dec 17, 2015 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01R
31/3842 (20190101); G01R 31/392 (20190101) |
Current International
Class: |
G01R
31/36 (20060101) |
Field of
Search: |
;702/63 ;701/22 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
J Schiffer et al. ; Journal of Power Sources 168(2007) 66-78. cited
by applicant.
|
Primary Examiner: Yi; Roy Y
Assistant Examiner: Aiello; Jeffrey
Attorney, Agent or Firm: BrooksGroup
Claims
What is claimed is:
1. A method of communicating an estimated state of health of a
battery to a vehicle component comprising: calculating a number of
charging equivalents for a number of healthy batteries of a
particular type and rating; determining a charging current
threshold value Th.sub.Ic, a lower bound voltage Th.sub.V, and an
upper bound current Th.sub.i from the calculated charging
equivalents; providing a vehicle comprising an ignition, a vehicle
battery, any number of sensors, and controller programmed to
calculate an estimated battery state of health of a the vehicle
battery; turning the vehicle ignition on; placing the vehicle
battery in a steady state; using the sensors to collect readings
including but not limited to a state of charge (SOC) reading, an
open circuit voltage (OCV) reading, and multiple groups of terminal
voltage readings and associated current readings from the vehicle
battery after the vehicle battery has reached a steady state; using
the controller to identify values that are terminal voltage
readings and place them in a data structure V which can be iterated
through; using the controller to identify values that are current
readings and place them in a data structure I which can be iterated
through; using the controller to identify all of the current
readings (BatIc) and associated terminal voltage readings (BatVc)
which are less than Th.sub.Ic; using the controller to determine
the value of the charging resistance equivalent .rho..sub.c by
using at least some of the multiple groups of terminal voltage and
associated current readings and OCV; using the controller to
calculate an estimated battery state of health using .rho..sub.c;
and using the controller to send a signal regarding the estimated
battery state of health to another component in the vehicle.
2. The method of claim 1 wherein determining a charging current
threshold value Th.sub.Ic, a lower bound voltage Th.sub.V, and an
upper bound current Th.sub.i from the calculated charging
resistance equivalents comprises: providing a number of charging
current threshold values within a range of charging current
threshold values; determining a ratio of a number of healthy
batteries having charging resistance equivalents falling above each
value within a number of values within the range of charging
current threshold values to a number of healthy batteries charging
resistance equivalents falling below each value within the number
of values within the range of charging current values; determining
a standard deviation of a charging resistance equivalent
.rho..sub.c amongst the batteries having a charging current less
than each value within a number of values within the range of
charging current threshold values; selecting a threshold value
Th.sub.Ic within the number of values within the range of charging
current threshold values which is associated with both a high ratio
and a small standard deviation; and using the selected threshold
value as a cut-off value for disabling .rho..sub.c estimation when
the battery current is lower than the selected threshold.
3. The method of claim 2 wherein a visual indication of reasonable
charging current threshold choices is formed, comprising: plotting
the standard deviation over the range of charging current threshold
values with a range of standard deviation values as a Y-axis; and
plotting each determined ratio over the range of charging current
threshold values with a ranged of ratio values as a Y-axis.
4. The method of claim 1 wherein using the controller to determine
the value of the charging resistance equivalent .rho..sub.c
comprises: the controller using all of the identified current
readings and associated terminal voltage readings>Th.sub.Ic to
solve for .rho..sub.c according to:
.function..function..function..times..times. ##EQU00003##
.rho..function..times..times..function..times..times.
##EQU00003.2## Where M.sub.c is a charge transfer coefficient of
the battery, C.sub.c is a normalized charging capacity of the
battery, and C.sub.n is a nominal capacity of the battery.
5. The method of claim 1 wherein using the controller to determine
the value of the charging resistance equivalent .rho..sub.c
comprises: the controller setting .rho..sub.c equal to a preset
value P.sub.default if the mean value of BatV is less than Th.sub.V
and 0 is less than the mean value of BatI when the mean value of
BatI is less than Th.sub.I, and SOC is equal to Th.sub.SOC or OCV
is equal to Th.sub.OCV.
6. The method of claim 1 wherein using the controller to determine
the value of the charging resistance equivalent .rho..sub.c
comprises: the controller setting .rho..sub.c equal to a preset
value P.sub.default if the mean value of BatV is not less than
Th.sub.V or 0 is not less than the mean value of BatI, or the mean
value of BatI is not less than Th.sub.I, or SOC is not equal to
Th.sub.SOC and OCV is not equal to Th.sub.OCV, then .rho..sub.c
equals a preset value P.sub.NA.
Description
TECHNICAL FIELD
The field to which the disclosure generally relates to includes
battery health estimation.
BACKGROUND
Numerous methods of battery health estimation exist.
SUMMARY OF ILLUSTRATIVE VARIATIONS
A number of illustrative variations may include a method of
estimating battery health including using a charging resistance
equivalent.
Other illustrative variations within the scope of the invention
will become apparent from the detailed description provided
hereinafter. It should be understood that the detailed description
and specific examples, while disclosing variations of the
invention, are intended for purposes of illustration only and are
not intended to limit the scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
Select examples of variations within the scope of the invention
will become more fully understood from the detailed description and
the accompanying drawings, wherein:
FIG. 1 illustrates a graphical representation of a current
threshold choice and associated values.
FIG. 2 illustrates a graphical representation of battery voltage
current matching and alignment as performed with generic data
structures by a controller according to a number of non-limiting
variations.
FIG. 3 illustrates a graphical representation of a logical flow
which may be used to determine what value to use as the charging
resistance equivalent according to a number of non-limiting
variations.
FIG. 4 is a schematic illustration of a vehicle including a
controller construct and arranged to estimate the health of a
battery using resistance estimation.
DETAILED DESCRIPTION OF ILLUSTRATIVE VARIATIONS
The following description of the variations is merely illustrative
in nature and is in no way intended to limit the scope of the
invention, its application, or uses.
Referring to FIG. 4, in a number of illustrative variations, a
vehicle 8 may include a controller 10, which is capable of
processing at least one of sequential logic or combinational logic,
may be provided. Additionally, a device capable of reading data
from memory and/or external storage devices 12 may be in electrical
communication with components including but not limited to the
controller. The controller may have onboard memory and may be in
electrical communication with an external data storage device 14 as
well as external memory devices 16. Any data which components might
access may be stored in memory, on a hard disk 18, or in any
storage means which is known in the art and may be accessible to
the controller. The controller may also be in electrical
communication with any number of sensors 20, 22, controllers 24,
26, batteries 28, 20, renewable energy sources 32 or other
electrical devices 34 and may have the ability to store and
timestamp data indicative of readings and/or signals from any
number of sensors. Any of the above stated components may be
operatively connected together receive and send signals, commands
and/or energy and/or provide input or contribute to the function
and/or operation of the other above stated components or to other
components in the vehicle. Furthermore, one or more of the aboved
stated components may be operatively connected by telematics to a
data center 11 outside of the vehicle constructed and arranged to
receive and send signals and commands to carry out the above stated
functions and operations of one or more of the components, and
constructed and arranged to perform the algorithms and methods
described herein.
In a number of illustrative variations, stored and/or actively
observed battery data may be used to determine the state of health
of the battery. Data used for this determination may include but is
not limited to any of a battery charging resistance equivalent, a
battery terminal voltage, a battery current, an open circuit
voltage, or a battery state of charge.
In a number of illustrative variations, a charging current
threshold is determined based on available data regarding the
battery type or rating as well as a battery operation data. The
threshold current may be used in filtering battery current values
which are lower than the threshold current from being used in
calculating a charging resistance equivalent--the use of low
battery current values in calculating the charging resistance may
lead to an inaccurate calculation of the charging resistance
equivalent. The controller may filter the input data by excluding
any vehicle battery current input data, and associated vehicle
battery terminal voltage input data which falls below a
predetermined current threshold value in further operations. Such
exclusion may be performed by simply flagging the data which is
desired to be excluded, actually removing the undesirable data from
its data structure, or by any method which is known in the art.
In a number of illustrative variations, and as shown in FIG. 1, if
the charging current threshold is to be chosen manually, a range of
reasonable charging current thresholds may be plotted as an X-axis;
a ratio of a number of healthy batteries having charging resistance
equivalents falling above each value within a number of values
within the range of charging current threshold values to a number
of healthy batteries charging resistance equivalents falling below
each value within the number of values within the range of charging
current values may be plotted over the range of charging current
thresholds, as a Y-axis; and a standard deviation of charging
resistance equivalents .rho..sub.c amongst the batteries having a
charging current less than each value within a number of values
within the range of charging current threshold values may be
plotted over the range of charging current thresholds, as a Y-axis.
The ratio of a number of healthy batteries having charging
resistance equivalents falling above each value within a number of
values within the range of charging current threshold values to a
number of healthy batteries charging resistance equivalents falling
below each value within the number of values within the range of
charging current values is plotted over the range of charging
current thresholds as line 100. The standard deviation of charging
resistance equivalents .rho..sub.c amongst the batteries having a
charging current less than each value within a number of values
within the range of charging current threshold values is plotted
over the range of charging current thresholds as line 102.
In a number of illustrative variations, a controller which is
capable of processing mathematics and at least one of sequential
logic or combinational logic, may be in electrical communication a
device which utilizes a battery. After an amount of time after the
device has entered a ready state, input data including but not
limited to any of a battery terminal voltage, a battery current, an
open circuit voltage, or a battery state of charge may be
collected, observed, received or determined by the controller. The
input data may be validated and/or organized by the controller and
conditional or sequential logic may be executed against the input
data to move any sequence of any program which the controller may
execute forward. The controller may then make any determinations
necessary for the estimation of the battery's state of health.
In a number of illustrative variations, and as illustrated by FIG.
2, a controller which is capable of processing mathematics and at
least one of sequential logic or combinational logic may obtain
input data and organize and filter the data. The input data
obtained may include but is not limited to a number of relatable
battery voltage values and battery current values. The controller
may place the battery voltage values and battery current values
data in a data structure EngValue which may be iterated through.
The controller may store indicators of the type of each piece of
input data which is stored in EngValue by placing flags to be
associated with each piece of data in EngValue in a data structure
EngName at a corresponding index. Specifically, in FIG. 2, the
flags placed in EngName are `1` to indicate that the value at the
corresponding index in EngValue is a voltage value, and `2` to
indicate that the value at corresponding index in EngValue is a
current value. After the controller has determined that EngValue
contains voltage values, the controller may then iterate through
EngName searching for a `1` flag followed by a `2` flag at
neighboring indices. If the controller finds such a pair, the value
in EngValue at the corresponding index to `1` in EngName is noted
as a voltage value with an associated current value by placing the
value in a data structure of valid battery voltage values BatV.
Similarly, the value in EngValue at the corresponding index to `2`
in EngName is noted as a current value with an associated voltage
value by placing the value in a data structure of valid battery
current values BatI at an index corresponding to that of the valid
battery voltage value placed in BatV. The controller may then
proceed with further operations which utilize battery voltage
values and battery current values, utilizing such values only from
the data structures BatV and BatI, respectively, thereby excluding
battery voltage values and battery current values which were found
to not be part of a voltage/current pair.
In a number of illustrative variations, and as illustrated by FIG.
3, a controller which is capable of processing mathematics and at
least one of sequential logic or combinational logic, may be housed
onboard a vehicle having a vehicle battery. After several units of
time after the vehicle engine's ignition, input data including ten
groups of vehicle battery terminal voltage and vehicle battery
current, an open circuit voltage and a vehicle battery state of
charge may be collected, observed, received or determined by the
controller and placed in data structures which may be iterated
through. The controller may then begin of organizing the battery
terminal voltage and battery current readings by first determining
that all the input data is available to the controller, and then
making sure that each vehicle battery terminal voltage and vehicle
battery current are correctly organized within their respective
data structures such that the two values might be correctly
associated with each other as their respective data structures are
iterated through. Such organization may entail excluding values
which are found to be without an associated partner value (for
example: a current value without an associated voltage value). At
this time, or at any other time, the controller may obtain
effective input data by filtering out any vehicle battery current
input data, and associated vehicle battery terminal voltage input
data, which falls below a predetermined current threshold value.
The controller may then use the effective input data to determine
which value should be used as a charging resistance equivalent in
further calculations.
In a number of illustrative variations, determining which value
should be used as a charging resistance equivalent in further
calculations comprises first determining whether all of the desired
input data is available, and if the desired input data is
available, filtering the input data and determining whether any
effective input data is left. If there is no effective input data
after filtering, the controller may then determine whether the mean
of all of the organized, available battery terminal voltage data is
less than a predetermined lower bound voltage, whether the mean of
all of the organized, available battery current data is greater
than zero and less than a predetermined upper bound current, and
whether the battery's state of charge is equal to a predetermined
default state of charge value or whether the open circuit voltage
is equal to a predetermined default open circuit voltage value. If
this condition is met, the controller may use a first default value
as a charging resistance equivalent in further calculations. If
this condition is not met, the controller may use a second default
value as a charging resistance equivalent in further
calculations.
In a number of illustrative variations, determining which value
should be used as a charging resistance equivalent in further
calculations comprises first determining whether all of the desired
input data is available, and if not, using a second default value
as a charging resistance equivalent in further calculations.
In a number of illustrative variations, if the controller
determines that all of the desired input data is available, and
that filtering results in a number of effective battery terminal
voltage and associated battery current values, the controller may
use determine the value for the charging resistance equivalent
.rho..sub.c as follows:
.function..function..function..times..times. ##EQU00001##
.rho..function..times..times..function..times..times.
##EQU00001.2## Where M.sub.C is a charge transfer coefficient of
the battery, C.sub.C is a normalized charging capacity of the
battery, and C.sub.n is a nominal capacity of the battery.
The following description of variants is only illustrative of
components, elements, acts, product and methods considered to be
within the scope of the invention and are not in any way intended
to limit such scope by what is specifically disclosed or not
expressly set forth. The components, elements, acts, product and
methods as described herein may be combined and rearranged other
than as expressly described herein and still are considered to be
within the scope of the invention.
Variation 1 may include a method of estimating the state of health
of a battery comprising: calculating a number of charging
equivalents for a number of healthy batteries of a particular type
and rating; determining a charging current threshold value
Th.sub.Ic, a lower bound voltage Th.sub.V, and an upper bound
current Th.sub.i from the calculated charging equivalents;
collecting readings including but not limited to a state of charge
(SOC) reading, an open circuit voltage (OCV) reading, and ten
groups of terminal voltage readings and associated current readings
from a vehicle battery after ignition-on; identifying values that
are terminal voltage readings and placing them in a data structure
V which can be iterated through; identifying values that are
current readings and placing them in a data structure I which can
be iterated through; identifying all of the current readings
(BatIc) and associated terminal voltage readings (BatVc) which are
less than Th.sub.Ic; using at least some of the ten groups of
terminal voltage and associated current readings and OCV to
determine the value of the charging resistance equivalent
.rho..sub.c; and using a controller to estimate the health of the
battery using .rho..sub.c.
Variation 2 may include the method of variation 1 wherein
determining a charging current threshold value Th.sub.Ic, a lower
bound voltage Th.sub.V, and an upper bound current Th.sub.i from
the calculated charging resistance equivalents comprises: providing
a number of charging current threshold values within a range of
charging current threshold values; determining a ratio of a number
of healthy batteries having charging resistance equivalents falling
above each value within a number of values within the range of
charging current threshold values to a number of healthy batteries
charging resistance equivalents falling below each value within the
number of values within the range of charging current values;
determining a standard deviation of a charging resistance
equivalent .rho..sub.c amongst the batteries having a charging
current less than each value within a number of values within the
range of charging current threshold values; selecting a threshold
value Th.sub.Ic within the number of values within the range of
charging current threshold values which is associated with both a
high ratio and a small standard deviation; and using the selected
threshold value as a cut-off value for disabling .rho..sub.c
estimation when the battery current is lower than the selected
threshold.
Variation 3 may include the method of variation 2 wherein a visual
indication of reasonable charging current threshold choices is
formed, comprising: plotting the range of charging current
threshold values as an X-axis; plotting the standard deviation over
the range of charging current threshold values with a range of
standard deviation values as a Y-axis; and plotting each determined
ratio over the range of charging current threshold values with a
ranged of ratio values as a Y-axis;
Variation 4 may include method of variation 1 wherein determining
the value of the charging resistance equivalent .rho..sub.c
comprises: using all of the identified current readings and
associated terminal voltage readings >Th.sub.Ic to solve for
.rho..sub.c according to:
.function..function..function..times..times. ##EQU00002##
.rho..function..times..times..function..times..times.
##EQU00002.2## where M.sub.C is a charge transfer coefficient of
the battery, C.sub.C is a normalized charging capacity of the
battery, and C.sub.n is a nominal capacity of the battery.
Variation 4 may include the method of variation 1 wherein
determining the value of the charging resistance equivalent
.rho..sub.c comprises: setting .rho..sub.c equal to a preset value
P.sub.default if the mean value of BatV is less than Th.sub.V and 0
is less than the mean value of BatI when the mean value of BatI is
less than Th.sub.I, and SOC is equal to Th.sub.soc or OCV is equal
to Th.sub.OCV.
Variation 5 may include the method of variation 1 wherein
determining the value of the charging resistance equivalent
.rho..sub.c comprises: setting .rho..sub.c equal to a preset value
P.sub.default if the mean value of BatV is not less than Th.sub.V
or 0 is not less than the mean value of BatI, or the mean value of
BatI is not less than Th.sub.I, or SOC is not equal to Th.sub.SOC
and OCV is not equal to Th.sub.OCV, then .rho..sub.c equals a
preset value P.sub.NA.
The above description of select variations within the scope of the
invention is merely illustrative in nature and, thus, variations or
variants thereof are not to be regarded as a departure from the
spirit and scope of the invention.
* * * * *